1. Related Application:
This application is related to application U.S. Ser. No. 637,103 filed even date entitled "DUAL Ring Segmented Block Tempering Ring."
2. Field of the Invention:
This invention relates to a tempering ring for supporting glass sheets and more specifically to a tempering ring that supports a hot shaped glass sheet on individually adjustable glass sheet support members that have pivoting head sections that conform to the peripheral contours of the glass sheet at its edge.
3. Brief Description of the Presently Available Technology:
The following patents relate to the handling of hot shaped glass sheets. Although some deal with glass bending techniques in general and others with tempering rings, all present apparatuses that support hot shaped glass sheets.
U.S. Pat. No. 3,163,514 to Golightly and U.S. Pat. No. 3,168,391 to Malobicky and Barch teach the use of dual rails on a skeletonized mold for a glass bending apparatus. The inner metal rail is notched and its top surface rail is disposed higher than that of the outer metal rail so that the glass sheet is supported directly and entirely by the inner rail.
U.S. Pat. No. 3,089,319 to Carson and White teaches a glass bending apparatus that includes a dual rail frame having a nonmetallic inner rail, such as Marinite or graphite, that will not fuse with the glass sheet during bending. Pivoting fingers support the flat glass sheet as it is lowering into the glass bending apparatus and shaped. When shaping is complete the fingers are no longer in contact with the glass sheet. As in the previously discussed patents, the rails are continuous except at the mold bend points.
U.S. Pat. No. 3,741,743 to Seymour teaches a shaping frame for both shaping and tempering operations. Dual steel rails support the glass sheet at its perimeter and are bridged by layers of steel mesh. The mesh must be sized so that it is strong enough to bridge the gap between the rails and support the glass sheet and open enough to allow adequate air circulation during tempering. The mesh is secured to the dual rail with wire elements.
U.S. Pat. No. 3,846,104 to Seymour teaches a shaping mold and a tempering ring. The lower outlining shaping mold is a stainless steel ring with a T-shaped cross section. The upper surface of the T-shaped ring is bonded to a refractory facing so as not to mar the heat softened glass during the shaping operation. The head section of the T member is continuous in the direction of the length of the rail. The tempering ring includes a single stainless steel rail with notched edges for direct support of the glass during tempering and with holes through it to increase air flow circulation.
U.S. Pat. No. 3,973,943 to Seymour teaches that the use of metal rails to contact a shaped glass sheet during a tempering operation has drawbacks. The difference in the cooling rates between the glass sheet and metal support sets up a retarded cooling rate at the glass to metal interface. This difference between the glass sheet cooling rate and the retarded cooling rate where the glass sheet rests directly on the rail (or rail section if it is notched) results in surface tensions in the glass which may cause breakage. To minimize or eliminate this problem, Seymour teaches a composite rail member including two side-by-side continuous rails with no spacing between them. The inner rail is a nonmetallic material having a lower heat transfer coefficient than the rigid steel outer rail to which it is mounted against. The upper edge of the inner rail is disposed above the upper edge of the outer steel rail so that only the inner rail contacts the shaped glass sheet.
All the discussed patents work adequately in normal shaping and tempering operations. A common problem associated with the support rings or rails of each patent is the need to have the edge of the tempering ring that supports the hot shaped glass sheet conform with the contours of the glass sheet as close as possible to provide a glass sheet support having a desired shape. This requires precise machining of glass support ring sections. It would be advantageous to have a tempering ring that supports the glass sheet with easily replaceable individual glass sheet support members that can be adjusted both longitudinally and vertically for fine adjustment to conform with the glass sheet contours thus minimizing if not eliminating any machining of the glass sheet support members. In addition, it would be beneficial if portions of the glass sheet support member could pivot so that when initially contacting the peripheral region of the glass sheet, they could rotate and assume the contour of the edge.
As used herein, "longitudinal" adjustment means movement along a support rail or rails about the central axis of the tempering ring. As used herein, "vertical" adjustment means up and down movement relative to the upper surface of a support rail or rails.